Chain saw bar



Oct. 18, 1966 J. w. EHLEN ET AL CHAIN SAW BAR 2 Sheets-Sheet 1 Original Filed Feb. 5, 1962 r, m r M Q i M 9 M1, $1M 3v Nv 5 Z A w 3 Z Q WY \W I, mx w INVEN TORS WHANN 8 Mc MAN/GAL Oct. 18, 1966 J. w. EHLEN ETAL CHAIN SAW BAR 2 Sheets-Sheet 2 Original Filed Feb. 5, 1962 R Q N m L w \m 5 5x98 ma m Na Qm .m m Nu NQ P Jack W fill/en, lo/1n R. Muir, Jab L Z/m mere);

INVENTORS. WHANN 8 McMAN/GAL Afforneys f'br A l/amfs.

United States Patent Continuation of application Ser. No. 170,949, Feb. 5,

1962. This application Nov. 26, 1965, Ser. No. 518,507 Claims. (Cl. 143-32) This is a continuation of application Serial No. 170,949, and now abandoned, filed February 5, 1962.

This invention relates to a bar or blade for chain saws and, more particularly, it relates to a bar for chain saws having a sprocket or sprockets on the nose end of the bar.

It is an object of the present invention to provide a chain saw bar having the advantages of the roller nose bars and the solid nose bars and not having the disadvantages of either.

It is another object of the present invention to provide an improved chain saw bar.

It is still another object of the present invention to provide a chain saw bar in which the saw chain is lifted off of the nose of the bar as it travels around it. This provides smooth roller action around the bar nose with a minimum of friction.

It is a further object of the present invention to provide a chain saw bar in which excessive bar and chain pounding is prevented. This is accomplished by the smooth transition from a sprocket at the end of the bar to the side plates thereof.

It is a still further object of the present invention to provide a chain saw bar on which chain jumping is prevented. Chain jumping is a problem in roller nose bars caused by the recesses or gaps between the roller and the main body of the 'bar. Conventional roller nose bars have these recesses or gaps cut transversely into the bar, inwardly of the roller, to prevent pounding of the chain as the chain comes off the roller. That is, it is the tendency for the chain to move inwardly toward the bar as it leaves the nose roller and with the gap in the bar pounding is reduced but jumping is increased. The jumping is increased in part by twigs and small branches which tend to protrude into the gap.

It is another object of the present invention to provide a chain saw bar having a low friction nose in the form of a sprocket which will permit saw chain cutting comparable to that in a solid nose bar. One of the problems encountered with the conventional roller nose bar is that the cutting performance just inwardly of the nose wheel is definitely decreased. That is, there is a recess ground into the bar just inwardly of the roller to prevent pounding and as the chain encounters this recess it is not supported by the bar and it fits into the recess so that it doesnt have the opportunity to cut properly In the present invention there is no such recess or gap and there is a smooth transition from the bar proper to a sprocket on the nose and back to the bar after the chain passes over the nose.

It is still another object of the present invention to provide an improved chain saw bar which is slim, having a unform thickness and which will have less tendency to bind than those heretofore provided.

It is a further object of the present invention to provide a chain saw bar of thetype referred to in the previous paragraphs and in which the chain is guided over the bar by a center groove formed in the longitudinal edges thereof.

It is a still further object of the present invention to provide a chain saw bar having the advantages described in the foregoing paragraphs and in which the chain is guided over the bar by straddling a central plate thereof which extends outwardly of side plates of the bar.

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It is another object of the present invention to provide a straddle type bar on which the chain straddles a central plate of the bar and is engaged with two spaced sprockets on the nose of the bar. This type of bar has the advantage of having the load on the nose more uniformly distributed than'on a single nose sprocket when the bar is performing a boring cut.

It is still another object of the present invention to provide a chain saw bar with an improved lirnbing'pcrformance. It has been found that when the present bars have been used for limbing, chains do not jump on them as they do on conventional roller nose bars and, further, the branches are not able to get between the bar and the chain as has been experienced with the roller nose type of bar.

It is a further object of the present invention to provide a chain saw bar which runs relatively cool on the nose during heavy usage.

It is a still further object of the present invention to provide a chain saw bar in which the necessity for flame hardening around the entire nose is eliminated. This is made possible by having a sprocket on the nose with which the chain is engaged, the sprocket being positioned so that the chain is carried off of the bar as it goes around the nose.

It is another object of the present invention to provide a chain saw bar having a loading device which maintains the correct tension on the chain when the bar is loosened on the chain saw engine, and after it is loosened it can again be tightened with the correct tension having been put on the chain while it was loose.

Further objects and advantages of the invention may be brought out in the following part of the specification, wherein small details have been described for the competence of disclosure, without intending to limit the scope of the invention which is set forth in the appended claims.

Referring to the accompanying drawings, which are for illustrative purposes only:

FIG. 1 is a side elevational view of a chain having parts thereof cut away; 7

FIG. 2 is a cross-sectional view taken as indicated by the line 2-2 of FIG. 1.

FIG. 3 is a fragmentary cross-sectional-plan view taken as indicated by the line 3-3 of FIG. 1.

FIG. 4 is an enlarged fragmentary cross-sectional view taken as indicated by the line 4-4 of FIG. 1;

FIG. 5 is a fragmentary view of a chain saw bar, illustrating the relationship of the bar to the chain saw holding bolts;

' FIG. 6 is an enlarged fragmentary cross-sectional view taken as indicated by the line 6-6 of FIG. 5 and illustrating a bar secured to a chain saw engine;

FIG. 7 is a side elevational view of another embodiment of the invention;

FIG. 8 is a cross-sectional view taken as indicated by the line 3-8 of FIG. 7.

' FIG. 9 is a fragmentary cross-sectional plan view taken as indicated by the line 9-9 of FIG. 7; and

FIG. 10 is a fragmentary cross-sectional view taken as indicated by the line 10-10 of FIG. 7.

Referring again to the drawings, there is shown in FIG. 1 a grooved or center guide chain saw bar, generally designated as 10. The bar is formed of three elongated flat plates, namely, a center plate 11 secured to outer identical right and left-hand plates 12 and 13 by welds or other suitable means. The outer plates are substantially coextensive longitudinally with the central plate at inner end 17 of the bar and transversely, or in the vertical direction in the drawings, they extend outwardly above and below the center plate to form a groove or chain guide 18. Adjacent the inner end 17 of saw bar 3 the bar is a longitudinal mounting slot 19 extending laterally through the bar.

In longitudinal alignment with the slot 19 is an extension thereof, extending outwardly from the inner end 17,

in the form of a generally rectangular groove 20 in the center plate 11. In the center plate 11, transversely above and below the slot 19 are wedge-shaped recessions 23 having their deepest ends extending toward the inner end 17, as may be seen in FIGS. 1 and 5. Three compressed parallel coil springs 24 extend longitudinally in the, groove 20 having their outer ends 25 in abutment with the outer end 26 of the groove 20. Their inner ends are in abutment with an end of a plug 30, slidably engageable in the groove 20 and the slot 19. In side elevation, as shown in FIGS. 1 and 5, the plugs 30 is a non-rectangular parallelogram, so formed, so that when it is free to move as far inwardly into the slot 19 asthe recesses 23, it will be forced into one of them, as shown in FIG. 1, to prevent it from falling out ofthe slot 19. That is, because of its non-rectangular configuration the springs 24 force it, as it moves longitudinally, to one transverse direction or the other into a stopping recess 23. Centrally within the plug 30 is a tool-engaging hole 31, and by which it may be moved, if necessary, within the slot 19 or the groove 20. The plug 30 and the springs 24 form a loading device for positioning the bar on the chain saw engine to properly tension the chain on the bar.

The bar contains a lubricating oil supply system for the saw chain and sprocket and, as may be seen in FIGS. 1, and 6, spaced transversely outwardly from the groove 19, are twolubricating oil entrance holes 32 extending laterally through the bar and being plugged with sintered metal 35 to filter the oil. Extending longitudinally through the holes 32 in central plate 11 are lubricating oil grooves 36 and 37. Adjacent their outer ends, as may be best seen in FIGS. 1 and 2, the grooves 36 and 37: are connected by a cylindrical hole 38 extending through inner plate 11. As shown in FIGS. 1-4, laterally outwardly of the hole 38 and connected therewith, in each of the outer plates 12 and 13, are longitudinally directed passages 41 and 42. These passages are formed outwardly by the outer plates and for a substantial part of their length, inwardly by outwardly facing channels 43 and 44 extending longitudinally in the passages 41 and 42,respectively, to positions adjacent each of their opposite ends. The passages 41 and 42 extend beyond ooncavely arced outer end 47 of center plate 11, within the side plates, and terminate in a bearing track 48 containing roller bearings 49. Outer ends 50 and 51 of the channels terminate immediately before the bearing track to permit the flow of oil between the outer plates 12 and 13 as well as into the bearing track.

The bearings are supported by an inner race 53, formed of a disc of the same thickness as inner plate 11, secured between outer plates 12 and 13 by rivets. An outer race 54 is formed by a sprocket 55 having a large central opening to fit over the roller bearings 49, positioned around the inner race 53.

The sprocket 55, mounted adjacent a substantially semicircular, outer end 56 of the bar between the outer plates, has a thickness slightly less than that of the center plate 11 so that it will rotate freely on the bearings. It has relatively large teeth 59, the outer surfaces of which being on an arc of a circle having its center at the center 58 of the sprocket on the longitudinal axis of the bar. The teeth have forwardly and rearwardly inclined edges 63 and 64, respectively. Between the teeth 59 are pockets 60 in which tangs of center links of the saw chain are engaged as the chain is fitted over the end 56 of the bar. The driving engagement of the sprocket by the chain commences as a center link tang moves into a pocket 61 intermediately outwardly of the end 47 of the center plate and the chain disengages itself from the sprocket as a tang movesoutwardlycf pocket 62 and onto the bar proper, the sprocket rotating in the clockwise direction on its axis and center 58.

The end are 56 on the bar has a center or end axis 57 on the longitudinal axis of the bar, offset longitudinally inwardly of the center or axis 58 of the sprocket 55, and the sprocket teeth extend sufficiently beyond the, are 56 so that the saw chain is carried off of it and rides solely on the sprocket. The teeth extend sufficiently beyond the are 56 to carry the chain of]? of it when they are long enough to make supporting contacts with their outer circumferential edges on the lower edges of the center links, and which are spaced longitudinally forwardly and rearwardlyof the tangs. Theteeth extend beyond the arc.56 through the arc of about 170 degrees, half of which extends transversely on each side of the longitudinal center of the bar.

In FIGS. 5 and 6, a portion of a chain saw engine housing 65 is shown. Extending from a chain saw bar mounting plate 66 are fixed bolts 67, as shown in FIG. 5, in the slot 19 of the bar 10. When the saw chain is on the bar with its center link tangs extending'into the opposite guide grooves 18 and with the tangs at t-heouter end being engaged with the sprocket 55, the inner loop of the chain is engaged with the engine driving sprocket, not shown. The springs 24 will thus force the plug 30 against the outer bolt 67 and in doing so will tension the endless saw chain the proper amount on the bar and the engine sprocket. Contact with the bolt provides a cam action on the plug to cause it to lock laterally in a recess 23. When the chain has been so tensioned, the bar is held in place and tightened on the chain saw engine by means of nuts 68 on bolts 67 as shown in FIG. 6.

The lubricating oil for the bearings 49 and for the saw chain is supplied fromthe engine through passage 71, shown in FIG. 6, and it flows through sintered metal filter 35 into upper passage 36, hole 38,, passages 41 and 42 onto the bearings, onto both sides of the sprocket and outwardly therefrom into the saw chain at the mostdesirable location, that is, where the chain starts to cut.

Because the lower side of the bar wears more than the upper side, the cutting takes place at the former, itis important that the bar be reversible. To make it reversible it is necessary that there be the lower lubricating oil passage 37, having therein a lower sintered metal plug 35, shown in FIG. 6 to be blocked olf by the mounting plates 65 and 72. However, when the saw baris reversed, the present lower plug 35 will be in communication with the conduit 71 so as to provide a passage for lubricating oil to the bearings and saw chain and the present upper plug will be blocked.

In operation, the saw chain travels around the saw bar with its side links riding onthe longitudinally directed edges of the side plates 12 and 13 and with its tangs on the center links riding freely within the grooves 18. As the chain moves from the side plates on the top of the bar in. FIG. 1, and onto the sprocket, the chain engages the sprocketteeth so that the side links are lifted physically off the side plates of the bar. As previously stated, it is for only approximately 170 degrees at the end of the bar that the side links do not make contact with the bar, but this lifting provides a substantially frictionless travel of the chain around the end 56, providing the advantage of the roller nose. bar.

Then, as the chain moves otf of the sprocket, the side links move evenly onto the lower edges of the side plates without moving inwardly, without pounding or jumping and without losing cutting efliciency. Thus, the disadvantages of the roller nose bar are eliminated.

In FIGS. 7-10, anotherembodiment of the invention is shown. Here, a laminated bar, generally designated as 75, is formed of three elongated flat plates, nam'ely, the,

center plate 78, secured to outer identical right and left? hand plates 79 and 80 bywelds, unshown, or by other suitable means. The outer plates are substantially coextensive longitudinally with thecentral plate at innerend 81 of the bar and transversely, or in the vertical direction in the drawings, the central plate 78 extends outwardly above and below the outer plates to form a tongue or chain track 84. Adjacent the inner end 81 of the bar, as in the first embodiment, the longitudinal mounting slot 19 extends laterally through the bar. This embodiment also contains the loading device 30 biased by the springs 24 in the groove 20.

At the inner end of the bar the lubricating means 35, 32, 36 and 37 are also provided. The lubricating grooves 36 and 37 terminate in the hole 38 extending laterally through the center plate 78. As best seen in FIGS. 7, 8 and 10, a groove 85 extends longitudinally from hole 38 in the center plate toward the outer arced end 86 of the center plate and bar. The groove 85 terminates within the center plate and joins a smaller longitudinally directed groove 87 terminating in an annular bearing track 90 containing roller bearings 91. Closing the groove 85 and fitted therein is an inwardly opening elongated channel member 92 to complete the lubricating system, the bearing track being open to both sides of the center plate.

As may be best seen in FIGS. 7 and 9, the outer plates 79 and 80 terminate in a concave are 93 inwardly of a substantially semicircular outer end 86 and laterally outwardly of groove 85 and channel 92, the latter forming a closure for the former extending longitudinally beyond the outer plates. The center 88 of the arced-end 86 is on the longitudinal axis of the bar.

Adjacent the outer end 86 are two large-teeth sprockets 96, sandwiching the center plate 78. The two sprockets are secured to an inner race 97 by rivets 98, the inner race being in longitudinal alignment with the center plate. An outer race 99 is formed radially outwardly of a cylindrical opening extending laterally through the center plate, the bearings being free to rotate between the two races and the sprockets being rotatable with the inner race 97, the thickness of the sprockets and the central plate being no greater than the thickness of the bar.

The sprocket axes centers 89 of the sprockets are on the longitudinal axis of the bar and are offset longitudinally outwardly of the center 88 of the arced-end 86 so that the teeth 102 of the sprockets extend radially beyond the curve of the arc 86. Here again, the teeth extend beyond the are 86 for approximately 170 degrees of the arc, half of which is above the longitudinal center line and the other half of which is below. As in the first embodiment, the extending teeth at the outer end of the bar lift the saw chain off of the end of the bar, in this case the center plate, to substantially eliminate friction between the bar nose and the chain.

In this embodiment the tangs of the side links of the chain straddle the track 84 and the chain rides on the outer surface of the track except after it engages the sprocket. In its travel along the track 84, the saw chain does not come into contact with the outer plates 79 and 80.

This arrangement of two sprockets on a straddle bar uniformly distributes the load imposed upon the sprocket assembly as the bar is performing a boring cut so as to make such cuts more stable. This embodiment also has the previously mentioned advantages of the single sprocket.

The invention and its attendant advantages will be understood from the foregoing description and it will be apparent that various changes may be made in the form, construction and arrangement of the parts of the invention without departing from the spirit and scope thereof or sacrificing its material advantages, the embodiments hereinbefore described being merely for the purposes of illustration.

We claim:

1. In a saw chain bar construction for supporting a saw chain, said bar including:

(a) upper and lower side edges providing surfaces to support and guide a saw chain .in a path along the plane of said bar;

(b) an end having at least a portion generated around an end axis,

(c) said end having surfaces which are continuations of said surfaces on said upper and lower edges; and (d) sprocket wheel means carried on said end in position for engagement with said chain traveling in said path over the end of said bar,

(c) said sprocket means being rotatable about its axis,

(f) said axis of said sprocket means being offset longi tudinally outwardly of said end axis,

(g) the sprocket teeth projecting outwardly beyond said end in an arc of said sprocket of approximately degrees to engage chain link surfaces to carry said chain off of said end,

(h) half of said are extending transversely on each side of the longitudinal center line of the bar.

2. The invention according to claim 1 in which:

said sprocket teeth have forward and rearward inclined edges, the teeth being narrower at their outer ends than at their roots.

3. The invention according to claim 1 in which:

said end of said bar is a substantially semicircular are having its center at said end axis.

4. The invention according to claim 1 wherein:

(a) said surfaces provided by said upper and lower side edges being formed on outer edges of said bar spaced by a groove,

(b) said end surfaces of said bar being continuations of said outer edges and being spaced by a continuation of said groove,

(c) said sprocket means being a sprocket carried in a pocket in said end.

5. The invention according to claim 4 in which:

said end of said bar is a substantially semicircular are having its center at said end axis.

6. The invention according to claim 5 in which:

said sprocket teeth have forward and rearward inclined edges, the teeth being narrower at their outer ends than at their roots.

7. In a saw chain bar construction for supporting a saw chain, said bar including:

(a) a pair of upper and a pair of lower longitudinally directed side edges, each pair of side edges being spaced by a groove, said edges being surfaces for engagement with side links of a saw chain and said groove being a path in which tangs of chain center links are adapted to ride freely;

(b) an end having a pair of transverse edges which are continuations of said upper and lower side edges,

(c) said end edges being spaced by a groove which is a continuation of said grooves spacing said side edges,

(d) said end being generated around an end axis on the longitudinal center line of said bar and being formed as a semicircular arc; and

(e) a sprocket carried in a pocket of said end, said pocket being formed of a recess with and inwardly of said end groove, said sprocket being rotatable about its center,

(f) said sprocket center being on said longitudinal center line and being olfset outwardly of said end axis,

(g) the teeth on said sprocket projecting outwardly from said end in an arc of said sprocket of approximately 170 degrees to engage center link surfaces outwardly of the tangs to carry said chain olf of said end,

(h) half of said arc extending transversely on each side of the longitudinal center line of the bar.

8. The invention according -to claim 7 in which:

said sprocket teeth have forward and rearward inclined edges, the teeth being narrower at their outer ends than at their roots.

9. In a saw chain bar construction for supporting a saw chain, said bar including:

(a) upper and lower side edges providing surfaces to support and guide a saw chain in a path along the plane of said bar;

(b) an end having at least a portion generated around an end axis,

(c) said end having surfaces which are continuations of said surfaces on said upper and lower edges;

(d) sprocket means carried at said end and rotatable around a sprocket axis; and

(e) sprocket teeth on said sprocket means,

(f) said sprocket axis being offset longitudinally outwardly of said end axis whereby an arcuate portion of the'ends of said sprocket teeth project outwardly beyond said end.

10. The invention according to claim 9 in which:

the 'arcuate portion of the ends of the sprocket teeth 5 which project outwardly beyond said end project in varying amounts from zero to maximum substantially along the longitudinal axis of said bar.

No references cited.

DONALD R. SCHRAN, Primary Examiner. 

1. IN A SAW CHAIN BAR CONSTRUCTION FOR SUPPORTING A SAW CHAIN, SAID BAR INCLUDING; (A) UPPER AND LOWER SIDE EDGES PROVIDING SURFACES TO SUPPORT AND GUIDE A SAW CHAIN IN A PATH ALONG THE PLANE OF SAID BAR; (B) AN END HAVING AT LEAST A PORTION GENERATED AROUND AN END AXIS, (C) SAID END HAVING SURFACES WHICH ARE CONTINUATIONS OF SAID SURFACES ON SAID UPPER AND LOWER EDGES; AND (D) SPROCKET WHEEL MEANS CARRIED ON SAID END IN POSITION FOR ENGAGEMENT WITH SAID CHAIN TRAVELING IN SAID PATH OVER THE END OF SAID BAR, (E) SAID SPROCKET MEANS BEING ROTATABLE ABOUT ITS AXIS, (F) SAID AXIS OF SAID SPROCKET MEANS OFFSET LONGITUDINALLY OUTWARDLY OF SAID END AXIS, (G) THE SPROCKET TEETH PROJECTING OUTWARDLY BEYOND SAID END IN AN ARC OF SAID SPROCKET OF APPROXIMATELY 170 DEGREES TO ENGAGE CHAIN LINK SURFACES TO CARRY SAID CHAIN OFF OF SAID END, (H) HALF OF SAID ARC EXTENDING TRANSVERSELY ON EACH SIDE OF THE LONGITUDINAL CENTER LINE OF THE BAR. 